1. Field of the Invention
This invention relates to a device for fixing a drill which is to be ground at its cutting edges, comprising a baseplate, a stand carried by said baseplate, a pivot pin mounted on said stand near its top end, and a gripping device, which is slidably fitted on said pivot pin and adapted to grip the drill which is to be ground.
2. Description of Prior Art
Such devices for fixing twist drills which are to be ground at their cutting edges are known from German Patent Specification No. 2833420 and comprise a baseplate, on which a carriage is slidably mounted to be movable in a horizontal direction by a screw. The carriage carries a stand, which is pivoted to the carriage on a vertical axis and near its top end carries a horizontal pivot pin, on which a device for gripping the drill to be sharpened is pivoted. The carriage has a tapped vertical bore, into which a clamping screw has been screwed, which extends through a slot formed in a baseplate of the angled stand. That screw serves to hold the stand in position. The baseplate is L-shaped and has an upwardly directed leg, which is formed with a clamping eye for receiving a bearing neck of a hand drill. In accordance with Laid-open German Application No. 2915601 for a patent of addition to German Pat. No. 2833420 the gripping device comprises two comblike gripping jaws, the teeth of which interengage and which are movable relative to each other by a clamping screw. Each gripping jaw is provided at that end which is adjacent to the stand with a wedge-shaped extension, which tapers toward the tip of the drill to be gripped, and with a bore, with which the gripping jaw can be fitted in different positions on the horizontal pivot pin. The extension of each gripping jaw comprises prism surfaces and the gripping jaws of the gripping device are displaceable relative to each other by means of transversely extending guide pins provided on a lateral retaining bar. The clamping screw is in screw-threaded engagement with the retaining bar.
It has been found that that device can be used for work requiring very high precision but the parts of said device must be made with high precision and closely matched so that the device is expensive and mainly suitable for commercial operations.